Cardiovascular diseases are the number one cause of death in civilized nations and according to recent research performed by World Health Organisation they account for more than 30% of all global deaths. Ischaemic heart disease, high blood pressure, arteriosclerosis, atherosclerosis and angina pectoris are just a very small list of irreversible heart disorders that affect people worldwide. By the time they are detected, the underlying cause is usually quite advanced and has progressed for several years. Unfortunately this problem delays and complicates treatment and in many cases it is impossible for patients to fully recover. Consequently there is a clear emphasis on detection and proper treatment of cardiovascular problems at a very early stage.
Electrocardiography (ECG) is the standard heart monitoring and diagnosis technique that allows easy measurement of the rate and regularity of heartbeats. However, ECG requires external electrodes to be attached to the surface skin of chest and also relatively expensive signal amplifiers to extract a decent signal for subsequent analysis. On the other hand, cardiovascular clinical research often depends on the understanding of the mechanical functionality of the heart, something which the electrical signal generates only limited information about.
An alternative to ECG is Ballistocardiography (BCG), in which mechanical movement of the body caused by the pumping of the heart is measured. BCG devices have been incorporated into daily life objects like beds, chairs or even modified weighing scales. More recently, seismocardiography (SCG) was introduced where sensors are directly attached on the human or animal chest to record chest vibrations. These known techniques provide an off-line solution for heart signal analysis and require dedicated, often bulky equipment.
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